When a user accesses a network resource, such as a website, user-perceived performance associated with such access can contribute to the overall user experience with the network resource, thereby affecting user decisions and even the bottom lines of the service providers. For instance, a user who experiences long response time at a retail website may be unwilling to visit the website again. Accurate and timely measurement of website performance can facilitate the identification and resolution of performance issues. However, existing performance measurement techniques focus primarily on the server-side performance that fails to account for client-side performance. Even when client-side performance is measured, such measurement is typically static and does not track user-perceived website performance as the users dynamically interact with the websites.